Existing motor vehicle door hinges are manufactured from a sheet metal since motor vehicle door hinges can be manufactured by using, for example, press forming at low cost (refer to, for example, PTL 1).
Alternatively, since the strength of existing motor vehicle door hinges formed from a sheet metal is low, door hinges of full-sized cars and high-end cars are manufactured from a mold steel. At that time, a mold steel formed through an extrusion process is used and is cut into pieces each having a desired length. The piece is formed into a desired shape through a cutting work (refer to, for example, PTL 2).